<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div></div>
</body>
</html>
<script>
// JS的三大核心：JS基础、DOM、BOM
  // DOM ->  Document Object Model
    // Document 指的是 html 相关代码

  // BOM -> Browser Object Model
    // 浏览器自带的行为：如 地址、刷新、前进/后退
</script>